RX 450H Air Suspension Conversion

vvpacc · March 6, 2021

41 minutes ago, Vadim said:

The replacement of air suspension to sprung suspension on RX450h mk3 is technically possible, but you need to replace both front and rear, and disable the air suspension controller.

The front is easy, because the spring is on the strut, and the fixing points are identical for air and sprung.

The problem is at the rear: since sprigs are separate from shock absorbers, and the lower rear wishbone is different for air and spring suspension, you’ll have to replace the wishbones(£50 each side used) add top spring mounts (£30 each side used), put springs (£100 each side new), and ideally replace shock absorbers (the ones for sprung suspension have longer travel). Add labour (about 3 hours front & rear) and all four wheels alignment (£60).

I also find that it is difficult to find used rear springs for this car, because they tend to snap with age.

With all the replacements considered, the rear suspension swap becomes quite expensive.

There are also reports online, that some traction safety systems may stop working if you remove the Air suspension system fuse.

Thank you. I am looking at a RX350 President, but I guess its similar to RX450 in terms of suspension. Labor is not an issue, i will probably get quoted about 40 GBP / hour at a friends place. Parts are, since I almost have no part numbers for the normal suspension. Found the air suspension onces + the air compressor. I mean, even at what you quoted with prices, swapping the entire suspensions seems cheaper than 1 airbag replacement + labor 🙂

Herbie · March 6, 2021

30 minutes ago, vvpacc said:

Thank you. I am looking at a RX350 President, but I guess its similar to RX450 in terms of suspension. Labor is not an issue, i will probably get quoted about 40 GBP / hour at a friends place. Parts are, since I almost have no part numbers for the normal suspension. Found the air suspension onces + the air compressor. I mean, even at what you quoted with prices, swapping the entire suspensions seems cheaper than 1 airbag replacement + labor 🙂

Have a look here at this place on eBay

A member here bought them for his RX300 conversion but they also do a set for the RX350. Also have a read of his thread below:

Vadim · March 6, 2021

1 hour ago, vvpacc said:

Thank you. I am looking at a RX350 President, but I guess its similar to RX450 in terms of suspension. Labor is not an issue, i will probably get quoted about 40 GBP / hour at a friends place. Parts are, since I almost have no part numbers for the normal suspension. Found the air suspension onces + the air compressor. I mean, even at what you quoted with prices, swapping the entire suspensions seems cheaper than 1 airbag replacement + labor 🙂

The 3rd generation of RX350 and RX450h have identical suspension parts. Weight is also roughly the same, so I would expect no issues with different springs / shocks characteristics.

vvpacc · March 7, 2021

23 hours ago, Herbie said:

Have a look here at this place on eBay

A member here bought them for his RX300 conversion but they also do a set for the RX350. Also have a read of his thread below:

Thank you. I already looked at the sellers eBay profile yesterday, also read through the thread. This kit seems to be for the previous generation, I am looking for MY2010, but should be similar price-wise. Intercars and autodoc can do wonders in terms of prices, but only once you have the part number.

vvpacc · March 7, 2021

22 hours ago, Vadim said:

The 3rd generation of RX350 and RX450h have identical suspension parts. Weight is also roughly the same, so I would expect no issues with different springs / shocks characteristics.

Thank you. That gives me confidence. I will be left only with being worried about the fuel consumption, but with 7000 miles per year, its not that much of a pain.

ColinBarber · March 7, 2021

22 hours ago, Vadim said:

Weight is also roughly the same, so I would expect no issues with different springs / shocks characteristics.

This is not the case. The hybrid model has 60 Kg more weight up front due to the inventor and cooling system, motors etc. and 80 Kg more at the rear due to the Battery pack over an AWD 350.

The springs/shocks have different part codes.

Vadim · March 7, 2021

ColinBarber is right: RX350 mk3 is about 1970kg, while RX450h mk3 is about 2110kg (depends on particular trim), which is +7% to the RX350 weight. I don't think the difference will be not noticeable at the front, however rear springs from RX350 may sag a bit too much in RX450h, particularly with full load. Still it is relatively simple to replace them or add insertions from a lifting kit to compensate at a later stage if the problem will appear.

I would not worry about the shocks, when the objective is to swap full air suspension to sprung suspension, even if the RX350 shocks are a tiny bit softer.

Vadim · March 8, 2021

Ultimately the weight difference is just a tankful of petrol (48kg) and one passenger (say, 92kg).

LucianVP · March 28, 2023

Hi guys,

Any updates on this one ? I had both top mounts done at Brian for my 450h however the knocking is still there on passenger side. I am planning to convert to sprung as I have bought a crashed 450h which has sprung suspension. Everything looks good, just wondering if i should expect any issues/errors after that. Also if someone knows how to disable the compressor/air system. Thanks

steve2006 · March 28, 2023

Should be a straight forward job to change over the struts, when my LS430 was converted it was just a case of pulling the air compressor fuse to disable it.

Leave the level sensors in place as removal may affect the headlight self levelling function.

LucianVP · March 28, 2023

Much appreciated. Just waiting for the rain to stop and I will get on with the job 😅

Alfamabo · June 26, 2023

On 9/23/2019 at 6:38 PM, inchley313 said:

I am currently in the process of fixing mine for the same reason. The bearing in the passenger side top mount has completely disintegrated (see picture) so I have just removed them and am sending them through to Brian at Orchard Engineering to have the bearing replaced. He has quoted £60 each plus postage to send them back.

The job of removing them is a damn site more simple than I originally imagined, I have just removed them both in under an hour, in the rain, (it always takes longer if it's raining) on axle stands. I didn't even have to remove the wheels to do it!

Sent from my SM-G950F using Tapatalk

Could you, please, tell which are dimensions/specifications or manufacturers code of the top mount replacement bearing?

Thanks

Marcox · November 4, 2023

On 3/6/2021 at 8:53 PM, Vadim said:

The replacement of air suspension to sprung suspension on RX450h mk3 is technically possible, but you need to replace both front and rear, and disable the air suspension controller.

The front is easy, because the spring is on the strut, and the fixing points are identical for air and sprung.

The problem is at the rear: since sprigs are separate from shock absorbers, and the lower rear wishbone is different for air and spring suspension, you’ll have to replace the wishbones(£50 each side used) add top spring mounts (£30 each side used), put springs (£100 each side new), and ideally replace shock absorbers (the ones for sprung suspension have longer travel). Add labour (about 3 hours front & rear) and all four wheels alignment (£60).

I also find that it is difficult to find used rear springs for this car, because they tend to snap with age.

With all the replacements considered, the rear suspension swap becomes quite expensive.

There are also reports online, that some traction safety systems may stop working if you remove the Air suspension system fuse.

I was leaning towards swapping my RX450h suspension from air to regular, but got concerned about the reports when it comes to traction control or anything else safety related. Has anyone experienced any problems after removing the air suspension system fuse?

KRR01 · January 28

Hi, did anybody do this? How was the computer system disabling? I have 2010 rx450h and also looking to do a swap, because my front air struts have failed and they are making a noise

steve2006 · January 28

My Celsior (LS430) was already converted on purchase using a kit from Strutmasters, the system was deactivated simply by removing the air suspension fuse so no warning lights.

KRR01 · January 30

On 1/28/2024 at 12:01 PM, steve2006 said:

My Celsior (LS430) was already converted on purchase using a kit from Strutmasters, the system was deactivated simply by removing the air suspension fuse so no warning lights.

thy dont offer kits for rx450h 😞 starting to think that it is not possible to convert from air to spring on 3rd gen rx

Marcox · January 30

13 minutes ago, KRR01 said:

thy dont offer kits for rx450h 😞 starting to think that it is not possible to convert from air to spring on 3rd gen rx

I did my rx450h few weeks ago, but with used parts sourced by my mechanic from RX on springs, just opted for new struts by KYB. I had an alternative for get all brand new parts by toyota/lexus, but overall cost estimate was 1/3 of RX's value

Stevo11 · January 30

How was the compressor disabled do you know? Did it affect other systems? I've read speculation on this but nothing concrete.

I have a knocking from the front left but I'm not convinced enough to pull the trigger on a new shock/airbag unit yet.

I'd first like to swop the top mounts side to side, anyone know if they sided?

Saim · March 29

Hi, I have Rx450 SE-L 2010 with air suspension. The front both suspensions are stuck in low position. I have tried adjusting the height manually but it didn’t work. The rear suspensions are working fine. I can hear air hissing from the front driver side when the compressor is on. I asked my mechanic and he suggested to change the whole air shock absorber which is quite expensive. I was wondering if one of the front air shock absorber is gone then why the other one is not working. Both stopped working at the same time. Are they connected or something? Need help before spending buying the full suspension.